a) \(64^x:16^x=256\)

\(\Rightarrow\left(2^6\right)^x:\left(2^4\right)^x=2^8\)

\(\Rightarrow2^{6x}:2^{4x}=2^8\)

\(\Rightarrow2^{6x-4x}=2^8\)

\(\Rightarrow2^{2x}=2^8\)

\(\Rightarrow2x=8\)

\(\Rightarrow x=4\)

b) \(\dfrac{-2401}{7^x}=-7\)

\(\Rightarrow\dfrac{-7^4}{7^x}=-7\)

\(\Rightarrow-7^{4-x}=-7\)

\(\Rightarrow7^{4-x}=7\)

\(\Rightarrow4-x=1\)

\(\Rightarrow x=4-1\)

\(\Rightarrow x=3\)

c) \(\dfrac{64}{\left(-4\right)^x}=-256\)

\(\Rightarrow\left(-4\right)^x=\dfrac{64}{-256}\)

\(\Rightarrow\left(-4\right)^x=-4\)

\(\Rightarrow\left(-4\right)^x=\left(-4\right)^1\)

\(\Rightarrow x=1\)

\(a) 64^x:16^x=256\\\Rightarrow (64:16)^x=256\\\Rightarrow 4^x=4^4\\\Rightarrow x=4\\---\)

\(b,\dfrac{-2401}{7^x}=-7\)

\(\Rightarrow7^x=-2401:\left(-7\right)\)

\(\Rightarrow7^x=343\)

\(\Rightarrow7^x=7^3\)

\(\Rightarrow x=3\)

\(c,\dfrac{64}{\left(-4\right)^x}=-256\)

\(\Rightarrow\left(-4\right)^x=64:\left(-256\right)\)

\(\Rightarrow\left(-4\right)^x=-\dfrac{1}{4}\)

\(\Rightarrow\left(-4\right)^x=\left(-4\right)^{-1}\)

\(\Rightarrow x=-1\)

#\(Toru\)

64^x.16^x=256¹²:1024

1024^x=4⁴³

4^5x=4⁴³

5x=43

x=8,6

\(64^x.16^x=256^{12}:1024\)

\(\Rightarrow\) \(\left(4^3\right)^x.\left(4^2\right)^x=\left(4^4\right)^{12}:4^5\)

\(\Rightarrow\) \(4^{3x}.4^{2x}=4^{48}:4^5\)

\(\Rightarrow\) \(4^{3x+2x}=4^{43}\)

\(\Rightarrow\) \(3x+2x=43\)

\(\Rightarrow\) \(\left(3+2\right)x=43\)

\(\Rightarrow\) \(5x=43\)

\(\Rightarrow\) \(x=\frac{43}{5}\)

64^x.16^x=256¹²:1024

1024^x=4⁴³

4^5x=4⁴³

5x=43

x=8,6

256 x 6=512 x 3

512 x 3=256 x 6

999 x 2>1000

512 x 5>1024

1024<512 x 5

1024=512 x 2

512=256 x 2

256=128 x 2

128=64 x 2

64=32 x 2

32=16 x 2

Đúng rồi

                    Đặt \(A=\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}\)

                    \(A=\frac{1}{2^3}+\frac{1}{2^4}+\frac{1}{2^5}+\frac{1}{2^6}+\frac{1}{2^7}+\frac{1}{2^8}\)

                \(2A=\frac{1}{2^2}+\frac{1}{2^3}+\frac{1}{2^4}+\frac{1}{2^5}+\frac{1}{2^6}+\frac{1}{2^7}\)

               \(2A-A=\left(\frac{1}{2^2}+\frac{1}{2^3}+\frac{1}{2^4}+\frac{1}{2^5}+\frac{1}{2^6}+\frac{1}{2^7}\right)-\left(\frac{1}{2^3}+\frac{1}{2^4}+\frac{1}{2^5}+\frac{1}{2^6}+\frac{1}{2^7}+\frac{1}{2^8}\right)\)

              \(A=\frac{1}{2^2}-\frac{1}{2^8}\)

           \(A=\frac{1}{4}-\frac{1}{256}=\frac{63}{256}\)

          \(\Rightarrow\frac{63}{256}.x=\frac{1}{512}=\frac{1}{2^9}\)

           \(\Rightarrow\frac{63}{2^8}.x=\frac{1}{2^9}\)

            \(\Rightarrow x=\frac{1}{2^9}:\frac{63}{2^8}=\frac{1}{2^9}.\frac{2^8}{63}=\frac{1}{2.63}=\frac{1}{126}\)

           Ủng hộ mk nha !!! ^_^

A=39760. b=158692,1211

ko bít lm bài này ak! dễ mak

bày cho câu b nha!

umk

a.1025

mk chịu câu b

*** mk nha

= (64/256 + 32/256 + 16/256 + 8/256 + 4/256 + 2/256) X x =1

= 126 X x = 1

x = 1 : 126

x= 1/126

nhớ k mình nha !!!